System and method for saving power using restricted access windows

ABSTRACT

Systems and methods for wireless communication are disclosed. In one aspect an access point includes a processor configured to generate a message identifying a time period in which the access point will enter a power save mode and ignore a packet sent from any wireless station, and a transmitter connected to the processor and configured to transmit the message to one or more wireless stations associated with the access point.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional Application No.61/730,948, entitled “System and Method for Saving Power UsingRestricted Access Windows,” filed Nov. 28, 2012, and U.S. ProvisionalApplication No. 61/731,407, entitled “System and Method for Saving PowerUsing Restricted Access Windows,” filed Nov. 29, 2012.

BACKGROUND

Field

The present application relates generally to wireless communications,and more specifically to systems, methods, and devices for saving powerusing restricted access windows.

Background

In many telecommunication systems, communications networks are used toexchange messages among several interacting spatially-separated devices.Networks may be classified according to geographic scope, which couldbe, for example, a metropolitan area, a local area, or a personal area.Such networks would be designated respectively as a wide area network(WAN), metropolitan area network (MAN), local area network (LAN), orpersonal area network (PAN). Networks also differ according to theswitching/routing technique used to interconnect the various networknodes and devices (e.g. circuit switching vs. packet switching), thetype of physical media employed for transmission (e.g. wired vs.wireless), and the set of communication protocols used (e.g. Internetprotocol suite, SONET (Synchronous Optical Networking), Ethernet, etc.).

Wireless networks are often preferred when the network elements aremobile and thus have dynamic connectivity needs, or if the networkarchitecture is formed in an ad hoc, rather than fixed, topology.Wireless networks employ intangible physical media in an unguidedpropagation mode using electromagnetic waves in the radio, microwave,infra-red, optical, etc. frequency bands. Wireless networksadvantageously facilitate user mobility and rapid field deployment whencompared to fixed wired networks.

The devices in a wireless network may transmit/receive informationbetween each other. The information may comprise packets, which in someaspects may be referred to as data units. The packets may includeoverhead information (e.g., header information, packet properties, etc.)that helps in routing the packet through the network, identifying thedata in the packet, processing the packet, etc., as well as data, forexample user data, multimedia content, etc. as might be carried in apayload of the packet.

SUMMARY

Various implementations of systems, methods and devices within the scopeof the appended claims each have several aspects, no single one of whichis solely responsible for the desirable attributes described herein.Without limiting the scope of the appended claims, some prominentfeatures are described herein. After considering this discussion, andparticularly after reading the section entitled “Detailed Description”one will understand how the features of various implementations allowsleep time for an access point.

One aspect of the disclosure provides an access point. The access pointincludes a processor configured to generate a message identifying a timeperiod in which the access point will ignore a packet from any wirelessstation, and a transmitter connected to the processor and configured totransmit the message to one or more wireless stations associated withthe access point.

Another aspect of the disclosure provides a method of wirelesscommunication. The method includes generating, at an access point, amessage identifying a time period in which the access point will ignorea packet from any wireless station. The method further includestransmitting the message from the access point to one or more wirelessstations associated with the access point.

Another aspect of the disclosure provides an access point. The accesspoint includes means for generating a message identifying a time periodin which the access point will ignore a packet from any wirelessstation. The access point further includes means for transmitting themessage to one or more wireless stations associated with the accesspoint.

Another aspect of the disclosure provides a non-transitory physicalcomputer storage including computer executable instructions configuredto implement a method for wireless communication by a station. Themethod includes generating, at an access point, a message identifying atime period in which the access point will ignore a packet from anywireless station. The method further includes transmitting the messagefrom the access point to one or more wireless stations associated withthe access point.

Another aspect of the disclosure provides a wireless station. Thestation includes a receiver configured to receive a message from anaccess point identifying a time period in which the access point willignore a packet from any wireless station, and a processor connected tothe receiver and configured to refrain from transmitting a packet to theaccess point during the identified time period.

Another aspect of the disclosure provides a method of wirelesscommunication. The method includes receiving, at a wireless station, amessage from an access point identifying a time period in which theaccess point will ignore a packet from any wireless station. The methodfurther includes refraining, at the wireless station, from transmittinga packet to the access point during the identified time period.

Another aspect of the disclosure provides a wireless station. Thestation includes means for receiving a message from an access pointidentifying a time period in which the access point will ignore a packetfrom any wireless station. The station further includes means forrefraining from transmitting a packet to the access point during theidentified time period.

Another aspect of the disclosure provides a non-transitory physicalcomputer storage including computer executable instructions configuredto implement a method for wireless communication by a station. Themethod includes receiving, at a wireless station, a message from anaccess point identifying a time period in which the access point willignore a packet from any wireless station. The method further includesrefraining, at the wireless station, from transmitting a packet to theaccess point during the identified time period.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a wireless communication system inwhich aspects of the present disclosure may be employed.

FIG. 2 illustrates an example of a wireless device that may be employedwithin the wireless communication system of FIG. 1.

FIG. 3 illustrates an example of components that may be included withinthe wireless device of FIG. 2 to transmit wireless communications.

FIG. 4 illustrates an example of components that may be included withinthe wireless device of FIG. 2 to transmit wireless communications.

FIG. 5 is a flowchart of a method of wireless communication inaccordance with one implementation.

FIG. 6 is a flowchart of a method of wireless communication inaccordance with one implementation.

FIG. 7 shows one implementation of the message identifying sleep timefor the access point.

FIG. 8 shows another implementation of the message identifying sleeptime for the access point.

FIG. 9 shows another implementation of the message identifying sleeptime for the access point.

FIG. 10 shows another implementation of the message identifying sleeptime for the access point.

FIG. 11 shows one implementation of the message identifying a minimumreserved time for the access window.

FIG. 12 shows one implementation of the message identifying a maximumreserved time for the access window.

DETAILED DESCRIPTION

Various aspects of the novel systems, apparatuses, and methods aredescribed more fully hereinafter with reference to the accompanyingdrawings. The teachings disclosure may, however, be embodied in manydifferent forms and should not be construed as limited to any specificstructure or function presented throughout this disclosure. Rather,these aspects are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the disclosure to thoseskilled in the art. Based on the teachings herein one skilled in the artshould appreciate that the scope of the disclosure is intended to coverany aspect of the novel systems, apparatuses, and methods disclosedherein, whether implemented independently of or combined with any otheraspect of the invention. For example, an apparatus may be implemented ora method may be practiced using any number of the aspects set forthherein. In addition, the scope of the invention is intended to coversuch an apparatus or method which is practiced using other structure,functionality, or structure and functionality in addition to or otherthan the various aspects of the invention set forth herein. It should beunderstood that any aspect disclosed herein may be embodied by one ormore elements of a claim.

Although particular aspects are described herein, many variations andpermutations of these aspects fall within the scope of the disclosure.Although some benefits and advantages of the preferred aspects arementioned, the scope of the disclosure is not intended to be limited toparticular benefits, uses, or objectives. Rather, aspects of thedisclosure are intended to be broadly applicable to different wirelesstechnologies, system configurations, networks, and transmissionprotocols, some of which are illustrated by way of example in thefigures and in the following description of the preferred aspects. Thedetailed description and drawings are merely illustrative of thedisclosure rather than limiting, the scope of the disclosure beingdefined by the appended claims and equivalents thereof.

Wireless network technologies may include various types of wirelesslocal area networks (WLANs). A WLAN may be used to interconnect nearbydevices together, employing widely used networking protocols. Thevarious aspects described herein may apply to any communicationstandard, such as WiFi or, more generally, any member of the IEEE 802.11family of wireless protocols. For example, the various aspects describedherein may be used as part of the IEEE 802.11ah protocol, which usessub-1 GHz bands.

In some aspects, wireless signals in a sub-gigahertz band may betransmitted according to the 802.11ah protocol using orthogonalfrequency-division multiplexing (OFDM), direct-sequence spread spectrum(DSSS) communications, a combination of OFDM and DSSS communications, orother schemes. Implementations of the 802.11 ah protocol may be used forsensors, metering, and smart grid networks. Advantageously, aspects ofcertain devices implementing the 802.11 ah protocol may consume lesspower than devices implementing other wireless protocols, and/or may beused to transmit wireless signals across a relatively long range, forexample about one kilometer or longer.

In some implementations, a WLAN includes various devices which are thecomponents that access the wireless network. For example, there may betwo types of devices: access points (“APs”) and clients (also referredto as stations, or “STAs”). In general, an AP serves as a hub or basestation for the WLAN and a STA serves as a user of the WLAN. Forexample, an STA may be a laptop computer, a personal digital assistant(PDA), a mobile phone, etc. In an example, an STA connects to an AP viaa WiFi (e.g., IEEE 802.11 protocol such as 802.11ah) compliant wirelesslink to obtain general connectivity to the Internet or to other widearea networks. In some implementations, an STA may also be used as anAP.

An access point (“AP”) may also comprise, be implemented as, or known asa NodeB, Radio Network Controller (“RNC”), eNodeB, Base StationController (“BSC”), Base Transceiver Station (“BTS”), Base Station(“BS”), Transceiver Function (“TF”), Radio Router, Radio Transceiver, orsome other terminology. The access point may be a main or relay basestation. A relay base station relays data between wireless stations andanother base station, being the main base station or another relay basestation.

A station “STA” may also comprise, be implemented as, or known as anaccess terminal (“AT”), a subscriber station, a subscriber unit, amobile station, a remote station, a remote terminal, a user terminal, auser agent, a user device, user equipment, or some other terminology. Insome implementations, an access terminal may comprise a cellulartelephone, a cordless telephone, a Session Initiation Protocol (“SIP”)phone, a wireless local loop (“WLL”) station, a personal digitalassistant (“PDA”), a handheld device having wireless connectioncapability, or some other suitable processing device connected to awireless modem. Accordingly, one or more aspects taught herein may beincorporated into a phone (e.g., a cellular phone or smartphone), acomputer (e.g., a laptop), a portable communication device, a headset, aportable computing device (e.g., a personal data assistant), anentertainment device (e.g., a music or video device, or a satelliteradio), a gaming device or system, a global positioning system device,or any other suitable device that is configured to communicate via awireless medium.

As discussed above, certain of the devices described herein mayimplement the 802.11ah standard, for example. Such devices, whether usedas an STA or AP or other device, may be used for smart metering or in asmart grid network. Such devices may provide sensor applications or beused in home automation. The devices may instead or in addition be usedin a healthcare context, for example for personal healthcare. They mayalso be used for surveillance, to enable extended-range Internetconnectivity (e.g. for use with hotspots), or to implementmachine-to-machine communications.

FIG. 1 illustrates an example of a wireless communication system 100 inwhich aspects of the present disclosure may be employed. The wirelesscommunication system 100 may operate pursuant to a wireless standard,for example the 802.11 ah standard. The wireless communication system100 may include an AP 104, which communicates with STAs 106.

A variety of processes and methods may be used for transmissions in thewireless communication system 100 between the AP 104 and the STAs 106.For example, signals may be sent and received between the AP 104 and theSTAs 106 in accordance with OFDM/OFDMA techniques. If this is the case,the wireless communication system 100 may be referred to as anOFDM/OFDMA system. Alternatively, signals may be sent and receivedbetween the AP 104 and the STAs 106 in accordance with CDMA techniques.If this is the case, the wireless communication system 100 may bereferred to as a CDMA system.

A communication link that facilitates transmission from the AP 104 toone or more of the STAs 106 may be referred to as a downlink (DL) 108,and a communication link that facilitates transmission from one or moreof the STAs 106 to the AP 104 may be referred to as an uplink (UL) 110.Alternatively, a downlink 108 may be referred to as a forward link or aforward channel, and an uplink 110 may be referred to as a reverse linkor a reverse channel.

The AP 104 may act as a base station and provide wireless communicationcoverage in a basic service area (BSA) 102. The AP 104 along with theSTAs 106 associated with the AP 104 that use the AP 104 forcommunication may be referred to as a basic service set (BSS). It shouldbe noted that the wireless communication system 100 may not have acentral AP 104, but rather may function as a peer-to-peer networkbetween the STAs 106. Accordingly, the functions of the AP 104 describedherein may alternatively be performed by one or more of the STAs 106.

The STAs 106 are not limited in type and may include a variety ofdifferent STAs. For example, as illustrated in FIG. 1, STAs 106 caninclude a cellular phone 106 a, a television 106 b, a laptop 106 c, anda number of sensors 106 d (e.g. a weather sensor or other sensor capableof communicating using a wireless protocol), to name a few.

FIG. 2 illustrates various components that may be utilized in a wirelessdevice 202 that may be employed within the wireless communication system100. The wireless device 202 is an example of a device that may beconfigured to implement the various methods described herein. Forexample, the wireless device 202 may comprise the AP 104 or one of theSTAs 106.

The wireless device 202 may include a processor 204 which controlsoperation of the wireless device 202. The processor 204 may also bereferred to as a central processing unit (CPU). Memory 206, which mayinclude both read-only memory (ROM) and random access memory (RAM),provides instructions and data to the processor 204. A portion of thememory 206 may also include non-volatile random access memory (NVRAM).The processor 204 typically performs logical and arithmetic operationsbased on program instructions stored within the memory 206. Theinstructions in the memory 206 may be executable to implement themethods described herein.

The processor 204 may comprise or be a component of a processing systemimplemented with one or more processors. The one or more processors maybe implemented with any combination of general-purpose microprocessors,microcontrollers, digital signal processors (DSPs), field programmablegate array (FPGAs), programmable logic devices (PLDs), controllers,state machines, gated logic, discrete hardware components, dedicatedhardware finite state machines, or any other suitable entities that canperform calculations or other manipulations of information.

The processing system may also include machine-readable media forstoring software. Software shall be construed broadly to mean any typeof instructions, whether referred to as software, firmware, middleware,microcode, hardware description language, or otherwise. Instructions mayinclude code (e.g., in source code format, binary code format,executable code format, or any other suitable format of code). Theinstructions, when executed by the one or more processors, cause theprocessing system to perform the various functions described herein.

The wireless device 202 may also include a transmitter 210 and areceiver 212 to allow transmission and reception of data between thewireless device 202 and a remote location. Further, the transmitters 210and the receiver 212 may be configured to allow transmission andreception of setup and/or configuration packets or frames between thewireless device 202 and a remote location including, for example, an AP.The transmitter 210 and receiver 212 may be combined into a transceiver214. An antenna 216 may be attached to the housing 208 and electricallycoupled to the transceiver 214. Alternatively, or additionally, thewireless device 202 may include an antenna 216 formed as part of thehousing 208 or may be an internal antenna. The wireless device 202 mayalso include (not shown) multiple transmitters, multiple receivers,multiple transceivers, and/or multiple antennas.

The wireless device 202 may also include a signal detector 218 that maybe used in an effort to detect and quantify the level of signalsreceived by the transceiver 214. The signal detector 218 may detect suchsignals as total energy, energy per subcarrier per symbol, powerspectral density and other signals. The wireless device 202 may alsoinclude a digital signal processor (DSP) 220 for use in processingsignals. The DSP 220 may be configured to generate a data unit fortransmission. In some aspects, the data unit may comprise a physicallayer data unit (PPDU). In some aspects, the PPDU is referred to as apacket or a frame.

The wireless device 202 may further comprise a user interface 222 insome aspects. The user interface 222 may comprise a keypad, amicrophone, a speaker, and/or a display. The user interface 222 mayinclude any element or component that conveys information to a user ofthe wireless device 202 and/or receives input from the user.

The various components of the wireless device 202 may be housed within ahousing 208. Further, the various components of the wireless device 202may be coupled together by a bus system 226. The bus system 226 mayinclude a data bus, for example, as well as a power bus, a controlsignal bus, and a status signal bus in addition to the data bus. Thoseof skill in the art will appreciate the components of the wirelessdevice 202 may be coupled together, or may accept or provide inputs toeach other using some other mechanism.

Although a number of separate components are illustrated in FIG. 2,those of skill in the art will recognize that one or more of thecomponents may be combined or commonly implemented. For example, theprocessor 204 may be used to implement not only the functionalitydescribed above with respect to the processor 204, but also to implementthe functionality described above with respect to the signal detector218 and/or the DSP 220. Further, each of the components illustrated inFIG. 2 may be implemented using a plurality of separate elements.

As discussed above, the wireless device 202 may comprise an AP 104 or aSTA 106, and may be used to transmit and/or receive communications. FIG.3 illustrates various components that may be utilized in the wirelessdevice 202 to transmit wireless communications. The componentsillustrated in FIG. 3 may be used, for example, to transmit OFDMcommunications. In some aspects, the components illustrated in FIG. 3are used to transmit data units with training fields with peak-to-poweraverage ratio is as low as possible, as will be discussed in additionaldetail below. For ease of reference, the wireless device 202 configuredwith the components illustrated in FIG. 3 is hereinafter referred to asa wireless device 202 a.

The wireless device 202 a may comprise a modulator 302 configured tomodulate bits for transmission. For example, the modulator 302 maydetermine a plurality of symbols from bits received from the processor204 or the user interface 222, for example by mapping bits to aplurality of symbols according to a constellation. The bits maycorrespond to user data or to control information. In some aspects, thebits are received in codewords. In one aspect, the modulator 302comprises a QAM (quadrature amplitude modulation) modulator, for examplea 16-QAM modulator or a 64-QAM modulator. In other aspects, themodulator 302 comprises a binary phase-shift keying (BPSK) modulator ora quadrature phase-shift keying (QPSK) modulator.

The wireless device 202 a may further comprise a transform module 304configured to convert symbols or otherwise modulated bits from themodulator 302 into a time domain. In FIG. 3, the transform module 304 isillustrated as being implemented by an inverse fast Fourier transform(IFFT) module. In some implementations, there may be multiple transformmodules (not shown) that transform units of data of different sizes.

In FIG. 3, the modulator 302 and the transform module 304 areillustrated as being implemented in the DSP 220. In some aspects,however, one or both of the modulator 302 and the transform module 304are implemented in the processor 204 or in another element of thewireless device 202.

As discussed above, the DSP 220 may be configured to generate a dataunit for transmission. In some aspects, the modulator 302 and thetransform module 304 may be configured to generate a data unitcomprising a plurality of fields including control information and aplurality of data symbols. The fields including the control informationmay comprise one or more training fields, for example, and one or moresignal (SIG) fields. Each of the training fields may include a knownsequence of bits or symbols. Each of the SIG fields may includeinformation about the data unit, for example a description of a lengthor data rate of the data unit.

Returning to the description of FIG. 3, the wireless device 202 a mayfurther comprise a digital to analog converter 306 configured to convertthe output of the transform module into an analog signal. For example,the time-domain output of the transform module 306 may be converted to abaseband OFDM signal by the digital to analog converter 306. The digitalto analog converter 306 may be implemented in the processor 204 or inanother element of the wireless device 202. In some aspects, the digitalto analog converter 306 is implemented in the transceiver 214 or in adata transmission processor.

The analog signal may be wirelessly transmitted by the transmitter 210.The analog signal may be further processed before being transmitted bythe transmitter 210, for example by being filtered or by beingupconverted to an intermediate or carrier frequency. In theimplementation illustrated in FIG. 3, the transmitter 210 includes atransmit amplifier 308. Prior to being transmitted, the analog signalmay be amplified by the transmit amplifier 308. In some aspects, theamplifier 308 comprises a low noise amplifier (LNA).

The transmitter 210 is configured to transmit one or more packets,frames, or data units in a wireless signal based on the analog signal.The data units may be generated using the processor 204 and/or the DSP220, for example using the modulator 302 and the transform module 304 asdiscussed above.

FIG. 4 illustrates various components that may be utilized in thewireless device 202 to receive wireless communications. The componentsillustrated in FIG. 4 may be used, for example, to receive OFDMcommunications. In some implementations, the components illustrated inFIG. 4 are used to receive packets, frames, or data units that includeone or more training fields, as will be discussed in additional detailbelow. For example, the components illustrated in FIG. 4 may be used toreceive data units transmitted by the components discussed above withrespect to FIG. 3. For ease of reference, the wireless device 202configured with the components illustrated in FIG. 4 is hereinafterreferred to as a wireless device 202 b.

The receiver 212 is configured to receive one or more packets, frames,or data units in a wireless signal.

In the implementation illustrated in FIG. 4, the receiver 212 includes areceive amplifier 401. The receive amplifier 401 may be configured toamplify the wireless signal received by the receiver 212. In someaspects, the receiver 212 is configured to adjust the gain of thereceive amplifier 401 using an automatic gain control (AGC) procedure.In some aspects, the automatic gain control uses information in one ormore received training fields, such as a received short training field(STF) for example, to adjust the gain. Those having ordinary skill inthe art will understand methods for performing AGC. In some aspects, theamplifier 401 comprises an LNA.

The wireless device 202 b may comprise an analog to digital converter402 configured to convert the amplified wireless signal from thereceiver 212 into a digital representation thereof. Further to beingamplified, the wireless signal may be processed before being convertedby the digital to analog converter 402, for example by being filtered orby being downconverted to an intermediate or baseband frequency. Theanalog to digital converter 402 may be implemented in the processor 204or in another element of the wireless device 202. In some aspects, theanalog to digital converter 402 is implemented in the transceiver 214 orin a data receive processor.

The wireless device 202 b may further comprise a transform module 404configured to convert the representation the wireless signal into afrequency spectrum. In FIG. 4, the transform module 404 is illustratedas being implemented by a fast Fourier transform (FFT) module. In someaspects, the transform module may identify a symbol for each point thatit uses.

The wireless device 202 b may further comprise a channel estimator andequalizer 405 configured to form an estimate of the channel over whichthe data unit is received, and to remove certain effects of the channelbased on the channel estimate. For example, the channel estimator may beconfigured to approximate a function of the channel, and the channelequalizer may be configured to apply an inverse of that function to thedata in the frequency spectrum.

In some aspects, the channel estimator and equalizer 405 usesinformation in one or more received training fields, such as a longtraining field (LTF) for example, to estimate the channel. The channelestimate may be formed based on one or more LTFs received at thebeginning of the data unit. This channel estimate may thereafter be usedto equalize data symbols that follow the one or more LTFs. After acertain period of time or after a certain number of data symbols, one ormore additional LTFs may be received in the data unit. The channelestimate may be updated or a new estimate formed using the additionalLTFs. This new or update channel estimate may be used to equalize datasymbols that follow the additional LTFs. In some aspects, the new orupdated channel estimate is used to re-equalize data symbols precedingthe additional LTFs. Those having ordinary skill in the art willunderstand methods for forming a channel estimate.

The wireless device 202 b may further comprise a demodulator 406configured to demodulate the equalized data. For example, thedemodulator 406 may determine a plurality of bits from symbols output bythe transform module 404 and the channel estimator and equalizer 405,for example by reversing a mapping of bits to a symbol in aconstellation. The bits may be processed or evaluated by the processor204, or used to display or otherwise output information to the userinterface 222. In this way, data and/or information may be decoded. Insome aspects, the bits correspond to codewords. In one aspect, thedemodulator 406 comprises a QAM (quadrature amplitude modulation)demodulator, for example a 16-QAM demodulator or a 64-QAM demodulator.In other aspects, the demodulator 406 comprises a binary phase-shiftkeying (BPSK) demodulator or a quadrature phase-shift keying (QPSK)demodulator.

In FIG. 4, the transform module 404, the channel estimator and equalizer405, and the demodulator 406 are illustrated as being implemented in theDSP 220. In some aspects, however, one or more of the transform module404, the channel estimator and equalizer 405, and the demodulator 406are implemented in the processor 204 or in another element of thewireless device 202.

As discussed above, the wireless signal received at the receiver 212comprises one or more data units. Using the functions or componentsdescribed above, the data units or data symbols therein may be decodedevaluated or otherwise evaluated or processed. For example, theprocessor 204 and/or the DSP 220 may be used to decode data symbols inthe data units using the transform module 404, the channel estimator andequalizer 405, and the demodulator 406.

Data units exchanged by the AP 104 and the STA 106 may include controlinformation or data, as discussed above. At the physical (PHY) layer,these data units may be referred to as physical layer protocol dataunits (PPDUs). In some aspects, a PPDU may be referred to as a packet,frame, or physical layer packet. Each PPDU may comprise a preamble and apayload. The preamble may include training fields and a SIG field. Thepayload may comprise a Media Access Control (MAC) header or data forother layers, and/or user data, for example. The payload may betransmitted using one or more data symbols. The systems, methods, anddevices herein may utilize data units with training fields whosepeak-to-power ratio has been minimized.

In wireless communications such as those specified in the IEEE 802.11family of wireless protocols, multiple stations share a transmissionmedium using a media access control protocol. A beacon frame, which isone of management and control frames that support data transfer, may beused to establish and maintain the communications in an orderly fashion.In some applications such as those specified in the 802.11ah protocol, arestricted access window may be used to define a period of time that anaccess point declares as reserved for a selected group of wirelessstations. However, the restricted access window does not provide sleeptime for the access point. Thus, it is beneficial to have a messagedefining a time period in which the access point will ignore, fail toconsider, or otherwise not accept a package from any wireless stations,in order to enable power save at the access point. As used herein, theterm “ignore” will be employed to describe the absence of action on thepart of the AP during the “sleep” or power save time designated by sucha message, as opposed to an active refusal to reply or consider anincoming packet, PPDU, or other data message.

In implementations as will be described below, an access point (AP)generates a message identifying a time period in which the access pointwill ignore a packet from any wireless station and sends the message tothe associated wireless stations. Upon receipt of the message, thewireless stations refrain from transmitting a packet to the access pointduring the identified time period. In one implementation, the message issent to all the wireless stations associated with the access point.These implementations may be applied in processes and standardsassociated with IEEE 802.11 and/or 802.11ah among others.

FIG. 5 is a flowchart of a method of wireless communication inaccordance with one implementation. The method 500 may be performed byan apparatus for wireless communication, such as the access point (AP)104 (shown in FIG. 1). At block 502, the method includes generating, atan access point, a message identifying a time period in which the accesspoint will ignore a packet from any wireless station. In oneimplementation, the message identifies a time period in which the accesspoint will ignore a data packet from any wireless station. The messagemay be sent as a part of a beacon frame, which is a management andcontrol frame used to establish and maintain the communications in anorderly fashion. The message may be generated by, for example, theprocessor 204 (shown in FIG. 2). Moving to block 504, the methodincludes transmitting the message from the access point to one or morewireless stations associated with the access point. The message may betransmitted by, for example, the transmitter 210 (shown in FIG. 2). Themethod 500 thus allows the AP to designate a sleep time. Someimplementations of the sleep time may comprise a period in which thereceiving circuitry, such as receiver 212, is powered down or otherwisedisabled to enable the access point to enter a power save mode. In otherimplementations, the AP may alternatively be commanded to activelyignore incoming packets from a group of wireless stations.

FIG. 6 is a flowchart of a method of wireless communication inaccordance with one implementation. The method 600 may be performed byan apparatus for wireless communication, such as the station 106 (shownin FIG. 1). At block 602, the method includes receiving, at a wirelessstation, a message from an access point identifying a time period inwhich the access point will enter sleep mode and ignore a packet or anyPPDUs from any wireless station. The message may be the messagetransmitted by an access point as described above with regard to FIG. 5.The message may be received by, for example, the receiver 212 (shown inFIG. 2). Moving to block 604, the method includes refraining, at thewireless station, from transmitting a packet to the access point duringthe time period identified by the message from the access point. Block604 may be performed by, for example, the processor 204 (shown in FIG.2).

The message identifying sleep time for the access point may be composedin various ways. FIG. 7 shows one implementation of the messageidentifying sleep time for the access point. The message 700 may betransmitted from an AP to associated wireless stations as describedabove with regard to FIG. 5. The message 700 may be transmitted usingany process and method suitable for transmissions from the AP to thestation.

In the illustrative implementation, the message defines a restrictedaccess window, a period of time that an access point declares asreserved for a selected group of wireless stations, such as onespecified in the 802.11 ah protocol. The message includes a RAW StartTime 702 indicating the start time of the restricted access window. Themessage also includes a RAW Duration 704 indicating the duration of therestricted access window. The message also includes a Group ID 706listing the selected group of wireless stations allowed to send a packetto the access point during the restricted access window.

In addition, the message includes a flag 708 for indicating that nowireless station is allowed to send a packet to the access point outsidea restricted access window. The flag 708 may include one bit which canbe set to a logic value of 0 or 1, wherein a logic value of 1 indicatesthat no wireless station is allowed to send a packet to the access pointoutside a restricted access window. By defining a restricted accesswindow and indicating that no access is allowed outside the restrictedaccess window, the message 700 thus defines any time outside thespecified restricted access window as a sleep time for the access point,lowering the access point power consumption. In one implementation, theflag 708 may additionally indicate that the access point will not sendany packet outside the restricted access window. This informs thewireless stations that both uplink and downlink communications are notpossible outside the restricted access window, allowing the stations togo to sleep mode.

Alternatively, the flag 708 may be defined as indicating that the accesspoint will ignore any packets from the selected group of wirelessstations identified by the Group ID 706.

FIG. 8 shows another implementation of the message identifying sleeptime for the access point. In the illustrative implementation, themessage 800 specifies a special type of restricted access window, whichis defined as a period of time that an access point declares that nowireless access station is allowed to send a packet to the access point.The message 800 thus includes a SRAW start time 802 indicating the starttime of the SRAW and a SRAW Duration 804 indicating the duration of theSRAW. Such a message 800 may alternatively indicate an access pointsleep time, during which no packets will be accepted in order tominimize power consumption.

FIG. 9 shows another implementation of the message identifying sleeptime for the access point. In the illustrative implementation, themessage defines a restricted access window, a period of time that anaccess point declares as reserved for a selected group or sector ofwireless stations, such as one specified in the 802.11ah protocol. Themessage includes a RAW Start Time 702 indicating the start time of therestricted access window and a RAW Duration 704 indicating the durationof the restricted access window.

In addition, the message includes a flag 902 for indicating that theselected group is an empty group. The flag 902 may include one bit whichcan be set to a logic value of 0 or 1, wherein a logic value of 1indicates that the selected group is an empty group. By defining arestricted access window and indicating that the selected group forrestricted access is empty, the message 900 thus defines a time windowas a sleep time for the access point. In one implementation, the flag902 may additionally indicate that the access point will not send anypacket outside the restricted access window. This informs the wirelessstations that both uplink and downlink communications are not possibleoutside the restricted access window, allowing the stations to go tosleep mode as well.

FIG. 10 shows another implementation of the message identifying sleeptime for the access point. In the illustrative implementation, themessage 1000 defines a restricted access window, a period of time thatan access point declares as reserved for a selected group of wirelessstations, such as one specified in the 802.11ah protocol. The messageincludes a RAW Start Time 702 indicating the start time of therestricted access window, a RAW Duration 704 indicating the duration ofthe restricted access window, and a Group ID 706 listing the selectedgroup of wireless stations allowed to send a packet to the access pointduring the restricted access window. The access point may set values tothe Group ID 706 such that the selected group does not include anywireless stations. In other words, the Group ID 706 identifies an emptygroup as the selected group. By defining a restricted access window andassigning no wireless station to the selected group for restrictedaccess, the message 1000 thus defines a time window a sleep time for theaccess point.

In one implementation, the Group ID 706 may include at least threeportions as defined in the 802.11 ah protocol. The first portion 1002includes a Page ID indicating the page index for hierarchicalassociation identification (AID) of the selected group of wirelessstations. The second portion 1004 includes a Block Offset indicating thestarting block index of the selected group. The third portion 1006includes a Block Range indicating the number of blocks for the selectedgroup starting from the block offset. In one implementation, it may bedefined that a value of 0 in all the three portions 1002, 1004 and 1006indicates that the selected group of wireless stations is empty.Alternatively, it may be defined that any combinations assigned to thethree portions, which will not result in a valid AID, may indicate thatthe selected group of wireless stations is empty. In one implementation,such combinations, which will not result in a valid AID may be, forexample, any fixed number between 6000 and 2^13.

The message illustrated above with regard to FIGS. 7-10 each lists theduration of the restricted access window. In some implementations, themessage may replace a field indicating fixed duration with a fieldindicating a minimum or maximum reserved time.

FIG. 11 shows one implementation of the message identifying a minimumreserved time for the access window. In the illustrative implementation,the message 1100 includes a minimum reserved duration indicating theminimum reserved time for the restricted access window. The message 1100thus granted access to the access point to a selected group of wirelessstations for the minimum reserved time. If any wireless station in theselected group wants to send data that exceeds the minimum reserved timeas identified in the message, the wireless station may send a request tothe access point to extend the active duration of the restricted accesswindow. For example, the wireless station may send a packet with a MoreData flag set to a logic value of 1, indicating that the station hasmore data to send. In response, the access point could send a messageindicating that the restricted access window is extended by a givenamount of time.

FIG. 12 shows one implementation of the message identifying a maximumreserved time for the access window. In the illustrative implementation,the message 1200 includes a maximum reserved duration indicating themaximum reserved time for the restricted access window. The message 1200thus granted access to the access point to a selected group of wirelessstations for the maximum reserved time. If the access point hasknowledge that all of the selected group of wireless stations are asleepbefore the maximum reserved time is reached, the access point may send amessage indicating that the restricted access window is terminatedearlier than the maximum reserved time. As a result, the access pointmay switch to a sleep mode during the remainder of the maximum reservedtime.

In some of the foregoing implementations, a message from an access pointspecifies a restricted access window, a period of time that the accesspoint declares as reserved for a selected group of wireless stations,such as one specified in the 802.11ah protocol. Alternatively, themessage may specify an access window during which access to the mediumis granted to all wireless stations. In other words, the access pointwill accept a packet from all wireless stations during the accesswindow. In one implementation, the message may further include a flagfor indicating no access outside the access window, such as the flag 708(see FIG. 7). This allows an access point to define active and inactiveperiods of time for the access point.

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like. Further, a “channel width” as used herein may encompass ormay also be referred to as a bandwidth in certain aspects.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover: a, b, c,a-b, a-c, b-c, and a-b-c.

The various operations of methods described above may be performed byany suitable means capable of performing the operations, such as varioushardware and/or software component(s), circuits, and/or module(s).Generally, any operations illustrated in the Figures may be performed bycorresponding functional means capable of performing the operations.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array signal (FPGA) or other programmable logic device(PLD), discrete gate or transistor logic, discrete hardware componentsor any combination thereof designed to perform the functions describedherein. A general purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

In one or more aspects, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored on or transmitted over as oneor more instructions or code on a computer-readable medium.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage media may be anyavailable media that can be accessed by a computer. By way of example,and not limitation, such computer-readable media can comprise RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium that can be used tocarry or store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Thus, in some aspects computer readable medium may comprisenon-transitory computer readable medium (e.g., tangible media). Inaddition, in some aspects computer readable medium may comprisetransitory computer readable medium (e.g., a signal). Combinations ofthe above should also be included within the scope of computer-readablemedia.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

The functions described may be implemented in hardware, software,firmware or any combination thereof. If implemented in software, thefunctions may be stored as one or more instructions on acomputer-readable medium. A storage media may be any available mediathat can be accessed by a computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Disk and disc, asused herein, include compact disc (CD), laser disc, optical disc,digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers.

Thus, certain aspects may comprise a computer program product forperforming the operations presented herein. For example, such a computerprogram product may comprise a computer readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. For certain aspects, the computer program product may includepackaging material.

Software or instructions may also be transmitted over a transmissionmedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition oftransmission medium.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

While the foregoing is directed to aspects of the present disclosure,other and further aspects of the disclosure may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. An access point comprising: a processorconfigured to generate a message identifying a restricted access windowthat the access point declares as reserved for a selected group ofwireless stations, the message further including a bit flag inassociation with the restricted access window, wherein the bit flag isset to a predetermined value that indicates that the selected group ofwireless stations that the restricted access window is reserved for isan empty group, and the message further indicating that the access pointwill ignore packets from any wireless station during the restrictedaccess window; and a transmitter connected to the processor andconfigured to transmit the message identifying the restricted accesswindow reserved for the selected group of wireless stations to one ormore wireless stations associated with the access point.
 2. The accesspoint of claim 1, wherein the access point is configured to beassociated with a plurality of wireless stations, and wherein thetransmitter is configured to transmit the message to the plurality ofwireless stations.
 3. The access point of claim 1, further comprisingthe message including a minimum reserved time for the restricted accesswindow, wherein the transmitter is further configured to, in response toa request from a wireless station to extend the restricted access windowbeyond the minimum reserved time, transmit a message indicating that therestricted access window is extended by a particular amount of time. 4.The access point of claim 1, further comprising the message including amaximum reserved time for the restricted access window, wherein thetransmitter is further configured to, upon detecting that all wirelessstations in the selected group are asleep before the maximum reservedtime is reached, transmit a message indicating that the restrictedaccess window is terminated.
 5. The access point of claim 1, furthercomprising the restricted access window indicating that the access pointwill ignore any packet during the restricted access window.
 6. Theaccess point of claim 1, further comprising the restricted access windowbeing defined by three fields, the three fields including a pageidentification field indicating a page index for hierarchicalassociation identification (AID) of the selected group, a block offsetfield indicating a starting block index of the selected group, and ablock range field indicating a number of blocks for the selected group,wherein the message indicates that the selected group is empty byassigning a value of 0 to the page identification field, the blockoffset field, and the block range field, or by assigning anycombinations of values to the three fields that will not result in avalid AID.
 7. A method of wireless communication, comprising:generating, at an access point, a message identifying a restrictedaccess window that the access point declares as reserved for a selectedgroup of wireless stations, the message further including a bit flag inassociation with the identified restricted access window, wherein thebit flag is set to a predetermined value that indicates that theselected group of wireless stations that the restricted access window isreserved for is an empty group, and the message further indicating thatthe access point will ignore packets from any wireless station duringthe restricted access window; and transmitting the message identifyingthe restricted access window reserved for the selected group of wirelessstations from the access point to one or more wireless stationsassociated with the access point.
 8. The method of claim 7, furthercomprising associating the access point with a plurality of wirelessstations, wherein the message is transmitted to the plurality ofwireless stations.
 9. The method of claim 7, further comprising themessage including a minimum reserved time for the restricted accesswindow, further comprising: receiving a request from a wireless stationto extend the restricted access window beyond the minimum reserved time;and transmitting a message from the access point to the wireless stationindicating that the restricted access window is extended by a particularamount of time.
 10. The method of claim 7, further comprising themessage including a maximum reserved time for the restricted accesswindow, the method further comprising: upon detecting that all wirelessstations in the selected group are asleep before the maximum reservedtime is reached, transmitting a message indicating that the restrictedaccess window is terminated.
 11. The method of claim 7, wherein therestricted access window indicates that the access point will ignore anypacket during the restricted access window.
 12. The method of claim 7,further comprising the restricted access window being defined by threefields, the three fields including a page identification fieldindicating a page index for hierarchical association identification(AID) of the selected group, a block offset field indicating a startingblock index of the selected group, and a block range field indicatingnumber of blocks for the selected group, wherein the message indicatesthat the selected group is empty by assigning a value of 0 to the pageidentification field, the block offset field, and the block range field,or by assigning any combinations of values to the three fields that willnot result in a valid AID.
 13. An access point, comprising: means forgenerating a message identifying a restricted access window that theaccess point declares as reserved for a selected group of wirelessstations, the message further including a bit flag in association withthe restricted access window, wherein the bit flag is set to apredetermined value that indicates that the selected group of wirelessstations that the restricted access window is reserved for is an emptygroup, and the message further indicating that the access point willignore packets from any wireless station during the restricted accesswindow; and means for transmitting the message identifying therestricted access window reserved for the selected group of wirelessstations to one or more wireless stations associated with the accesspoint.
 14. A non-transitory computer readable storage medium comprisingcomputer executable instructions configured to implement a method forwireless communication by a station, the method comprising: generating,at an access point, a message identifying a restricted access windowthat the access point declares as reserved for a selected group ofwireless stations, the message further including a bit flag inassociation with the restricted access window, wherein the bit flag isset to a predetermined value that indicates that the selected group ofwireless stations that the restricted access window is reserved for isan empty group, and the message further indicating that the access pointwill ignore packets from any wireless station during the restrictedaccess window; and transmitting the message identifying the restrictedaccess window reserved for the selected group of wireless stations fromthe access point to one or more wireless stations associated with theaccess point.
 15. A wireless station comprising: a receiver configuredto receive a message from an access point identifying a restrictedaccess window that the access point declares as reserved for a selectedgroup of wireless stations, the message further including a bit flag inassociation with the restricted access window, wherein the bit flag isset to a predetermined value that indicates that the selected group ofwireless stations that the restricted access window is reserved for isan empty group, and the message further indicating that the access pointwill ignore packets from any wireless station during the restrictedaccess window; and a processor connected to the receiver and configuredto refrain from transmitting a packet to the access point during theidentified time period.
 16. The wireless station of claim 15, furthercomprising the message further including a minimum reserved time for therestricted access window, wherein the processor is further configured totransmit a request to the access point to extend the restricted accesswindow beyond the minimum reserved time.
 17. The wireless station ofclaim 15, further comprising the message further including a maximumreserved time for the restricted access window, wherein the receiver isfurther configured to receive a message from the access point indicatingthat the restricted access window is terminated.
 18. The wirelessstation of claim 15, wherein the restricted access window indicates thatthe access point will ignore any packet during the restricted accesswindow.
 19. The wireless station of claim 15, further comprising therestricted access window being defined by three fields, the three fieldsincluding a page identification field indicating a page index forhierarchical association identification (AID) of the selected group, ablock offset field indicating a starting block index of the selectedgroup, and a block range field indicating number of blocks for theselected group, wherein the message indicates that the selected group isempty by assigning a value of 0 to the page identification field, theblock offset field, and the block range field, or by assigning anycombinations of values to the three fields that will not result in avalid AID.
 20. A method of wireless communication, comprising:receiving, at a wireless station, a message from an access pointidentifying a restricted access window that the access point declares asreserved for a selected group of wireless stations, the message furtherincluding a bit flag in association with the restricted access window,wherein the bit flag is set to a predetermined value that indicates thatthe selected group of wireless stations that the restricted accesswindow is reserved for is an empty group, and the message furtherindicating that the access point will ignore packets from any wirelessstation during the restricted access window; and refraining, at thewireless station, from transmitting a packet to the access point duringthe identified time period.
 21. The wireless station of claim 20,further comprising the message including a minimum reserved time for therestricted access window, the method further comprising transmitting arequest from the wireless station to the access point to extend therestricted access window beyond the minimum reserved time.
 22. Thewireless station of claim 20, further comprising the message including amaximum reserved time for the restricted access window, furthercomprising receiving, at the wireless station, a message from the accesspoint indicating that the restricted access window is terminated. 23.The method of claim 20, wherein the restricted access window indicatesthat the access point will ignore any packet during the restrictedaccess window.
 24. The method of claim 20, further comprising therestricted access window being defined by three fields, the three fieldsincluding a page identification field indicating a page index forhierarchical association identification (AID) of the selected group, ablock offset field indicating a starting block index of the selectedgroup, and a block range field indicating number of blocks for theselected group, wherein the message indicates that the selected group isempty by assigning a value of 0 to the page identification field, theblock offset field, and the block range field, or by assigning anycombinations of values to the three fields that will not result in avalid AID.
 25. A wireless station, comprising: means for receiving amessage from an access point identifying a restricted access window thatthe access point declares as reserved for a selected group of wirelessstations, the message further including a bit flag in association withthe restricted access window, wherein the bit flag is set to apredetermined value that indicates that the selected group of wirelessstations that the restricted access window is reserved for is an emptygroup, and the message further indicating that the access point willignore packets from any wireless station during the restricted accesswindow; and means for refraining from transmitting a packet to theaccess point during the identified time period.
 26. A non-transitoryphysical computer storage comprising computer executable instructionsconfigured to implement a method for wireless communication by astation, the method comprising: receiving, at a wireless station, amessage from an access point identifying a restricted access window thatthe access point declares as reserved for a selected group of wirelessstations, the message further including a bit flag in association withthe restricted access window, wherein the bit flag is set to apredetermined value that indicates that the selected group of wirelessstations that the restricted access window is reserved for is an emptygroup, and the message further indicating that the access point willignore packets from any wireless station during the restricted accesswindow; and refraining, at the wireless station, from transmitting apacket to the access point during the identified time period.